INACTIVATION OF ETAMYCIN BY A NOVEL ELIMINATION MECHANISM IN STREPTOMYCES-LIVIDANS

An enzyme responsible for inactivating the peptidolactone antibiotic e tamycin was partially purified from extracts of Streptomyces lividans. On-line liquid chromatography-electro spray mass spectrometry showed that the product of the enzyme-catalyzed reaction had a different rete ntion time but the same mass as etamycin. Reaction of etamycin in 1.0 M NaOH gave a mixture consisting of the product expected from hydrolys is of the lactone bond and a product corresponding to that from the en zyme reaction, Label from (H2O)-O-18 was incorporated into the hydroly sis product but not into the product of the enzyme reaction, An enzyme -catalyzed elimination reaction is proposed, and is supported by evide nce for the structure of the resulting dehydrobutyrine peptide from co mbined liquid chromatography-tandem mass spectrometry (LC-MS-MS) and H -1 NMR spectroscopy.